1. Field of the Invention
This invention relates to a method and apparatus for remote energizing of power storage devices and particularly to a method and apparatus employing small apparatus for remote energizing of power storage devices using RF frequencies based on wireless frequencies. The method and apparatus of this invention preferably employs at least one antenna that has an effective area greater than its physical area to harvest energy.
2. Description of the Prior Art
Contactless electrical connections are well known in the field of portable electrical devices. For example, portable motorized toothbrushes typically contain a rechargeable battery, which is charged by induction. The inductive charging device is also called an electromagnetic, non-contact type battery charging device. The inductive charging device is advantageous in that it cannot be hindered by a bad electrical contact unlike the charging device that requires an electrical connection. Inductive charging devices typically consist of inductive coupler for transferring energy from a primary side of the inductive coupler on a charging device to a secondary side of the inductive coupler on the electronic device. Examples of inventions utilizing inductive charging include U.S. Pat. No. 6,284,651, U.S. Pat. No. 6,310,465 and U.S. Pat. No. 5,952,814. A major problem with inductive charging is that the charging device needs to be in close proximity to the electronic device in order to energized power storage devices in the electronic device.
To overcome the problems associated with inductive charging, charging devices using RF electromagnetic field radiated into free space have been described. U.S. Pat. No. 6,127,799 describes a charge storage device that is charged by exposing the charge storage device to an RF electromagnetic field radiated into free space within a closed system. The charge storage device includes one or more dipole antennas disposed on the device and adapted to receive the radiated RF electromagnetic field. One or more bridge rectifiers are connected to the antennas for rectifying the received RF electromagnetic field into a DC output current. The DC output current produced by the rectifier is used to energize the charge storage device.
As disclosed in U.S. Pat. No. 6,127,799, the antennas may be one or more dipole antennas which are combined to form at least two subsets of dipole antenna element arrays, wherein one subset may be oriented at an acute or a right angle with respect to at least one other subset. The antennas or dipole antennas may be placed on more than one outside surface of the charge storage device, which enclose an acute or a right angle with respect to each other. The use of RF energy and antennae to develop remote charging using the technology disclosed in U.S. Pat. No. 6,127,799 has a shortcoming in that the power conversion efficiency of the antenna array in the disclosed invention is dependent on the number of dipoles. Also, the size of the dipole antennas for the device do not make it practical for the majority of portable electronic devices (e.g., cellular telephones, portable electronic games, digital cameras and the like). In this prior disclosure, the dipole antennas are used to cover more than one side of a battery that has a width of 12.5 cm.
An approach to overcoming the problems of prior art is through the use of antennas formed on electronic chips. Examples of prior art that disclosed on-chip antennas include U.S. Pat. No. 4,857,893 and U.S. Pat. No. 6,373,447.
The preferred approach as detailed in U.S. Pat. No. 4,857,893 is to use a deposition technique that effectively creates a single monolithic chip assembly that includes all of the circuitry necessary to produce a functionally complete transponder unit. This patent discusses the use of magnetic film inductors on the chip to allow a reduction in the number of turns, and thereby make the fabrication of such inductors feasible. This patent referenced Soohoo, “Magnetic Thin Film Inductors For Integrated Circuit Applications”, IEEE Transactions in Magnetic, Vol. MAG-15, No. 6, pp. 1803-1805 (November 1979). Another technique referenced in this patent was in Salch and Qureshi, “Permalloy ThinFilm Inductors”, Electronic Letters, Vol. 6, No. 26, pp. 850-852 (Dec. 31, 1970).
This patent discusses the construction of the antenna on a chip as follows: A 10-turn square spiral coil for use at 10 MHz is constructed having an outer diameter of 1 cm×1 cm. The conducting path width is 0.005 inches. The spacing between turns is 0.001 in. The copper path is deposited by vacuum evaporation and then thickness is built up to about 25 micrometers by electroplating. Two permalloy magnetic films, having a thickness of from 1000-3000 Angstroms, surround the conductors, one on top, and the other on the bottom. The film is evaporated in an orienting magnetic field in such a way that the long dimension is parallel to the field, and thus it is the easy direction of magnetization of the film. When a high-frequency current passes in the coil, the magnetic films are driven in a hard direction, and the two magnetic films around each conductor act as a magnetic core enclosing a 1-turn coil. The effect of the magnetic films is to increase the inductance of the coil in addition to its free-space inductance. The magnetic permeability is quite large, since the films are driven in the hard direction. Further, an insulating silicon-monoxide layer (SiO, 10,000 A thick) separates each magnetic film from the conducting path.
The problem with the approach as disclosed by U.S. Pat. No. 4,857,893 is the need to deposit a permalloy magnetic film, or other suitable material having a large magnetic permability and electrical insulating properties in order increase the inductance of the coil. This increases the cost and complexity of the antenna of a chip. Furthermore, it limits the ability to shrink the size of the antenna because of the need for magnetic film layers between the antenna coil(s).
U.S. Pat. No. 6,373,447 discloses the use of one or more antennas that are formed on an integrated circuit (IC) chip and connected to other circuitry on the IC chip. Antenna configurations are disclosed that include loop, multi-turn loop, square spiral, long wire, or dipole. The antenna as disclosed could be formed to have two or more segments, which can selectively be connected to one another to alter an effective length of the antenna. Furthermore, two antennas may be formed in two different metallization layers separated by an insulating layer. A major shortcoming of this prior art is that the inventors teach that the antenna's transmitting and receiving strength “is proportional to the number of turns and area of the loop.”
U.S. patent application Ser. No. 09/951,032 (Mickle) which is a CIP of U.S. Pat. No. 6,289,237 discloses an antenna on a chip that has an effective area greater than its physical area. The effective area of the antenna is made greater than its physical area through the use of an LC tank circuit in the antenna. This is accomplished through the use in the (1) antenna of inter-electrode capacitance and inductance and jointly or severally the (2) parasitic capacitance and inductance of the chip (die) to form the LC tank circuit. The benefit of utilizing the inter-electrode capacitance and inductance and parasitic capacitance and inductance to form the LC tank circuit is that no additional discrete circuitry is required to provide the antenna with an effective area greater than its physical area. More important, the use of the LC tank circuit means that use of magnetic films around each antenna conductor is not required. This simplifies the production of the antenna on a chip and potentially allows the design of ultra-small antenna on a chip.
U.S. Pat. No. 6,289,237, the disclosure of which is incorporated herein by reference, discloses apparatus and a related method for energizing a remote station from a base station through the use of a suitable type of transmitted energy including RF power wherein the remote station does not contain a source of stored energy or a wired connection to a source of energy. Microprocessor controllers may be provided on the base station and remote station.
United States continuation-in-part application Ser. No. 09/951,032 which was based on the application which became U.S. Pat. No. 6,289,237 discloses the use of a chip containing an onboard antenna. The disclosure of this application is incorporated herein by reference.
Copending provisional application Ser. Nos. 60/406,541 and 60/411,845, the disclosures of which are incorporated herein by reference, disclose apparatus and methods for remote energizing of power storage devices and, particularly, small apparatus for remote energizing of power storage devices, using RF energy.
There remains a need for a method and associated apparatus which may be of small size and be structured to provide remote energizing of power storage devices employing RF energy preferably wherein the RF energy is within the frequency ranges employed in wireless fidelity (WiFi). There is a further need for such a device wherein the apparatus incorporates at least one antenna on the remote device which contains the power storage device which has an effective area greater than its physical one antenna in order to facilitate harvesting energy.
There is a need for small remote power charger device and associated method that have a means for receipt of transmitted energy from the environment and energizing power storage devices wherein the power charger device is not dependent on inductive charging.
Furthermore, there is a need for a small remote power charger device and associated method having a means for receipt of transmitted energy from the environment and energizing power storage devices using one or more antenna(e) on a substrate.
Finally, there is a need for a small remote power charger device and associated method that uses one or more antenna(e) on a substrate wherein the strength of the antenna is not dependent on magnetic induction or number of turns and area of the loop of the antenna.